The investigation into what caused the fire is well underway, and although there is no official cause, Saturday afternoon an official with the Office of Fire Investigation said the fire may have been sparked accidentally by roofers doing repairs.

Saturday afternoon, firefighters were still putting out hot spots at this Northwest Side strip mall left gutted by an extra alarm fire.

"We can't get to it because of the way the roof is caved in, for safety reasons I'm not letting anybody in there," said Battalion Chief Michael Smandra, Chicago Fire Department.

As firefighters continued to squash the building's rekindling debris, authorities continued their investigation into the blaze. Fire investigators now say was caused by workers using propane torches to complete repairs on the mall's roof.

"We were inside the store and the smoke started coming because we knew they were working there and then we saw the flame between the roof and the drop ceiling of our store," said Sammy Dajani, Mid America Furniture.

Dajani and her family own Mid America Furniture Store which is one of several businesses destroyed by the fire.

Her son, Feras Dajani, was inside their store when he says an escaping roofer warned him of the danger.

"He said, 'Call 911.' They saw it was up there," Feras Dajani said.

Saturday, investigators interviewed several people.

It's unclear if the roofers, who witnesses said left their truck behind when they fled the scene of the fire, were among them.

No one was injured in the Friday afternoon fire that started around 4 p.m.

The fire not only produced raging flames but also black smoke. It enveloped the whole neighborhood and could be seen for miles.

Jerry Zanyed says his tobacco shop and liquor store were spared because of a firewall.

"We just opened opened up two months ago. They strip mall was recovering, finally, from the first fire and now this just wiped out the other half," he said.

And as the curious gather to see the destruction for themselves, some neighborhood residents hope businesses in the popular strip mall will rebuild.

"This store served a lot of different people, so I just hope we can get something back," said neighborhood resident Bridget Michelle.

The Chicago Police Department said their bomb and arson unit has joined the investigation, but they are not looking at the incident as a criminal act.